Children happiness factor

Solution 1:

I can tell you the thing I've seen.

My dweller wives just gave birth to 6 children in the last minute (I was afk in the game for some hours after they were pregnant).

The overall happyness was 86% at 102 people. After the birth I've got 108 people with 86% happyness. If those children would count to it, it should be lower. But it was still the same.

I think they count after they are adults.

Solution 2:

Neither children nor dwellers outside the vault (including exploring or new ones) count towards overall happiness.

Solution 3:

All adults 100% happiness. 2 children at 50%. Total happiness 99%. They must count a little.